Epidemiological Survey Of The Pathogens Of Mycoplasma-type Cow Mastitis In Parts Of Northern China During 2010-2016

Bovine Mastitis is one of the important diseases which restrict the stable development of the dairy industry.A variety of pathogenic bacterium can induce the occurrence of bovine mastitis.As one of the pathogenic bacterium,Mycoplasma has been paid much attention in recent years.During the research of Mycoplasma mastitis pathogenic epidemiology of large-scale dairy farms located in Heilongjiang province,Liaoning province,the Ningxia Huizu Autonomous Region,the Inner Mongolia Autonomous Region,Tianjin City,the author found out the positive rate of Mycoplasma bovine mastitis,as well as the relationship between the rate and the cow's ages,parities,the investigation of area and time.The paper could provide the experiment basis for clinical prevention of Mycoplasma bovine mastitis.Firstly,the author designed two pairs of special primers(531U28/1371L25)and(17U26/556L22),which took the B0W43 00590 gene sequence of Mycoplasma bovine(M.bovis)GN1168 strain(GenBankand: CP019639.1)and the outer membrane protein coding genes of Mycoplasma leachii(M.Leachii)GN407 strain(GenBankand: HQ699892.1)as reference.And the author ultimately established the two PCR detection methods of the M.bovis and M.leachii by optimizing the reaction conditions such as PCR annealing temperature.According to the results of specific test,the above-mentioned two PCR methods could achieve the amplification of M.bovis and M.leachii specifically,and had no cross reactions with other Mycoplasma(such as Mycoplasma mycoides subsp.Capricolum,Mycoplasma ovipneumoniae,Mycoplasma.mycoides subsp.Mycoides Small Colony Type,Mycoplasma capricolum subsp.capripneumoniae).Sensitivity test results showed that the minimum concentration of the M.bovis and M.leachii were 104 CCU(color change unit)and 105 CCU,respectively.Compliance test results showed that,by testing two strains of standard positive Mycoplasma,the positive results were consistent with the results we got from the Mycoplasma cultivation method.And the coincidence rate came to 100 percent.These results confirmed that the PCR established in this study is a fast,sensitive,specific and reliable method for detecting M.bovis and M.leachii.Secondly,the author used the two PCR methods to test the 539 milk samples with clinical mastitis of 28 large-scale dairy farms in 5 regions in China.The overall results showed that 41 Mycoplasma were tested with the positive rate of 7.61% and 2 M.Leachii were tested among the total number,with the positive rate of 0.371%.The rest parts of results were 39 M.bovis,with the positive rate of 7.24%.The results of regional test revealed that among 275 samples from Heilongjiang province in 12 cattle herds,2 M.leachii and 19 M.bovis positive samples were detected.M.bovis and M.leachii were not detected in 97 samples from Liaoning province and the Ningxia Huizu Autonomous Region.5 M.bovis positive samples were detected and M.leachii were not detected in 54 samples from Tianjin City.15 M.bovis and no M.leachii were detected in 113 samples from Inner Mongolia Autonomous Region.The annual test results indicated that according to investigated the 40 samples in 2010,the author detected 1 M.Leachii with the positive rate of 2.50% and 4 M.Bovis with the positive rate of 12%.Among the 85 samples in 2011,the author detected 1 M.Leachii with the positive rate of 1.17% and 4 M.bovis with the positive rate of 12.9%.And among the 414 samples in 2016,there were no M.Leachii detected,and 24 M.bovis were detected with the positive rate of 12.9%.According to the results of the research of the relationship between the Mycoplasma mastitis and the cow's age and parities,the author got some information.Firstly,among the 118 samples from the cattle with the age of 2 to 3,5 cows were positive and the rate was 4.24%.Among the 180 samples from the cattle with the age of 3 to 5,12 cows were positive and the rate was 6.67%.And among the 241 samples from the cattle with the age of 5 to 7,24 cows were positive and the rate was 9.96%.Secondly,when came to the various parities,within the 118 samples from the cattle with the parity of 1 to 2,3 cows were the positive and 2.54% was the positive rate.Within the 180 samples from the cattle with the parity of 3 to 4,12 cows were the positive and 6.67% was the positive rate.And within 241 samples from the cattle with the parity of 5 to 6,27 cows were the positive and 11.20% was the positive rate.In conclusion,the test successfully established the PCR detection methods of M.bovis and M.leachii.The Mycoplasma Bovine Mastitis had a low and diffuse morbidity in some northern areas of our country.It showed an increasing tendency,and had positive correlation with the cow's age and parity.